#include <stdio.h>
#include <stdlib.h>

int main() 
{
	double num1, num2, result;
	char ope;
	printf("please input:");
	scanf("%lf %c %lf", &num1, &ope, &num2);
	switch (ope)
	{
		case '+':
			result = num1 + num2;
			break;
		case '-':
			result = num1 - num2;
			break;
		case '*':
			result = num1 * num2;
			break;
		case '/':
			result = num1 / num2;
			break;
		default:
			printf("invalid input\n");
			return -1;
	}
	printf("result:%.2lf\n", result);
	return 0;
}